Title of Invention

DATA CABLE WITH CROSS-TWIST CABLED CORE PROFILE

Abstract Cables 117 including a plurality of twisted pairs of insulated conductors 103 and a core 101 disposed between the plurality of twisted pairs of insulated conductors 103 so as to separate at least one of the plurality of twisted pairs of insulated conductors 103 from others of the plurality of twisted pairs of insulated conductors 103. In one example, a cable 117 may include a jacket having a plurality of protrusions 165. In another example, the core 101 may include one or more pinch points 111 to facilitate breaking of the core 101. In yet another example, two or more cables 117 may be bundled, and possibly twisted, together to form a bundled cable.
Full Text BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to high-speed data communications cables using at
least two twisted pairs of wires. More particularly, it relates to cables having a central
core defining plural individual pair channels.
2. Discussion of Related Art
High-speed data communications media include pairs of wire twisted together to
form a balanced transmission line. Such pairs of wire are referred to as twisted pairs.
One common type'of conventional cable for high-speed data communications includes
multiple twisted pairs that may be bundled and twisted (cabled) together to form the
cable.
Modern communication cables must meet electrical performance characteristics
required for transmission at high frequencies. The Telecommunications Industry
Association and the Electronics Industry Association (TIA/EIA) have developed
standards which specify specific categories of performance for cable impedance,
attenuation, skew and crosstalk isolation. When twisted pairs are closely placed, such as
in a cable, electrical energy may be transferred from one pair of a cable to another. Such
energy transferred between pairs is referred to as crosstalk and is generally undesirable.
The TIA/EIA have defined standards for crosstalk, including TWEIA-568 A. The
International Electrotechnical Commission (IEC) has also defined standards for data
communication cable crosstalk, including ISO/IEC 11801. One nigh-performance
standard for 100 Ω cable is ISO/IEC 11801, Category 5, another is ISO/IEC 11801
Category 6.
In conventional cable, each twisted pair of a cable has a specified distance
between twists along the longitudinal direction, mat distance being referred to as the pair
lay. When adjacent twisted pairs have the same pair lay and/or twist direction, they tend
to lie within a cable more closely spaced than when they have different pair lays and/or
twist direction. Such close spacing may increase the amount of undesirable crosstalk
which occurs between adjacent pairs. Therefore, in some conventional cables, each

twisted pair within the cable may have a unique pair lay in order to increase the spacing
between pairs and thereby to reduce the crosstalk between twisted pairs of a cable. Twist
direction may also be varied.
Along with varying pair lays and twist directions, individual solid metal or woven
metal pair shields are sometimes used to electromagnetically isolate pairs. Shielded
cable, although exhibiting better crosstalk isolation, is more difficult and time consuming
to install and terminate. Shielded conductors are generally terminated using special
tools, devices and techniques adapted for the job.
One popular cable type meeting the above specifications is Unshielded Twisted
Pair (UTP) cable. Because it does not include shielded conductors, UTP is preferred by
installers and plant managers, as it may be easily installed and terminated. However,
conventional UTP may fail to achieve superior crosstalk isolation, as required by state of
the art transmission systems, even when varying pair lays are used.
Another solution to the problem of twisted pairs lying too closely together within
a cable is embodied in a shielded cable manufactured by Belden Wire & Cable Company
as product number 1711A. This cable includes four twisted pair media radially disposed
about a "star"-shaped core. Each twisted pair nests between two fins of the "star"-shaped
core, being separated from adjacent twisted pairs by the core. This helps reduce and
stabilize crosstalk between the twisted pair media. However, the core adds substantial
cost to the cable, as well as material which forms a potential fire hazard, as explained
below, while achieving a crosstalk reduction of only about 5 dB. Additionally, the close
proximity of the shield to the pairs within the cable requires substantially greater
insulation thickness to maintain desired electrical characteristics. This adds more
insulation material to the construction and increases cost.
In building design, many precautions are taken to resist the spread of flame and
the generation of and spread of smoke throughout a building in case of an outbreak of
fire. Clearly, it is desired to protect against loss of life and also to minimize the costs of
a fire due to the destruction of electrical and other equipment. Therefore, wires and
cables for in building installations are required to comply with the various flammability
requirements of the National Electrical Code (NEC) and/or the Canadian Electrical Code
(CEC).
Cables intended for installation in the air handling spaces (i.e. plenums, ducts,
etc.) of buildings are specifically required by NEC or CEC to pass the flame test

specified by Underwriters Laboratories Inc. (UL), UL-910, or it's Canadian Standards
Association (CSA) equivalent, the FT6. The UL-910 and the FT6 represent the top of
the fire rating hierarchy established by the NEC and CEC respectively. Cables
possessing this rating, generically known as "plenum" or "plenum rated", may be
substituted for cables having a lower rating (i.e. CMR, CM, CMX, FT4, FT1 ortheir
equivalents), while lower rated cables may not be used where plenum rated cable is
required.
Cables conforming to NEC or CEC requirements are characterized as possessing
superior resistance to ignitability, greater resistant to contribute to flame spread and
generate lower levels of smoke during fires than cables having a lower fire rating.
Conventional designs of data grade telecommunications cables for installation in plenum
chambers have a low smoke generating jacket material, e.g. of a PVC formulation or a
fluoropolymer material, surrounding a core of twisted conductor pairs, each conductor
individually insulated with a fluorinated ethylene propylene (FEP) insulation layer.
Cable produced as described above satisfies recognized plenum test requirements such as
the "peak smoke" and "average smoke" requirements of the Underwriters Laboratories,
Inc., UL910 Steiner test and/or Canadian Standards Association CSA-FT6 (Plenum
Flame Test) while also achieving desired electrical performance in accordance with
EIA/TIA-568A for high frequency signal transmission.
While the above-described conventional cable, including the Belden 1711A cable
due in part to their use of FEP, meets all of the above design criteria, the use of
fluorinated ethylene propylene is extremely expensive and may account for up to 60% of
the cost of a cable designed for plenum usage.
The solid, relatively large core of the Belden 1711A cable may also contribute a
large volume of fuel to a cable fire. Forming the core of a fire resistant material, such as
FEP, is very costly due to the volume of material used in the core. Solid flame
retardant/smoke suppressed polyolefin may also be used in combination with FEP.
However, solid flame retardant/smoke suppressed polyolefin compounds commercially
available all possess dielectric properties inferior to that of FEP. In addition, they also
exhibit inferior resistance to burning and generally produce more smoke than FEP under
burning conditions than FEP.
SUMMARY OF INVENTION

According to one embodiment, a data cable comprises a plurality of twisted pairs
of insulated conductors, including a first twisted pair and a second twisted pair, and a
core disposed between the plurality of twisted pairs of insulated conductors so as to
separate the first twisted pair from the second twisted pair along a length of the data
cable, wherein the core comprises at least one pinch point where-a diameter of the core is
substantially reduced relative to a maximum diameter of the core.
In another embodiment, a shielded cable comprises a plurality of twisted pairs of
insulated conductors, including a first twisted pair and a second twisted pair, a core
disposed between the plurality of twisted pairs of insulated conductors so as to separate
the first twisted pair from the second twisted pair along a length of the data cable, a dual-
layer jacket enclosing the core and the plurality of twisted pairs of insulated conductors,
the dual-layer jacket including a first jacket layer and a second jacket layer, and a
conductive shield disposed between the first jacket layer and the second jacket layer.
According to another embodiment, a bundled cable comprises a first cable
including a plurality of twisted pairs of insulated conductors and a first separator
arranged between the plurality of twisted pairs so as to separate one of the plurality of
twisted pairs from others of the plurality of twisted pairs, the first cable having a first
jacket, and a second cable including a plurality of twisted pairs of insulated conductors
and a second separator arranged between the plurality of twisted pairs so as to separate
one of the plurality of twisted pairs from others of the plurality of twisted pairs, the
second cable having a second jacket, wherein each of the first and second jackets
comprises a plurality of protrusions. In one example, the plurality of protrusions of each
of the first and second jackets are outwardly projecting, and the first and second jackets
are adapted to mate with one another so as to lock the first cable to the second cable. In
another example, the plurality of protrusions of the first or second jacket are inwardly
projecting.
According to another embodiment, a cable comprises a plurality of twisted pairs
of insulated conductors including a first twisted pair and a second twisted pair, a core
disposed between the plurality of twisted pairs of insulated conductors so as to separate
the first twisted pair from the second twisted pair, and a jacket surrounding the plurality
of twisted pairs of insulated conductors and the core, wherein the first twisted pair has a
- first twist lay and a first insulation thickness, wherein the second twisted pair has a
second twist lay, smaller than the first twist lay, and a second insulation thickness, and


wherein a skew between the first and second twisted pairs is less than about 7
nanoseconds.
BRIEF DESCRIPTION OF ACCOMPANYING DRA WINGS
In the drawings, which are not intended to be drawn to scale, each identical or
nearly identical component that is illustrated in various figures is represented by a like
numeral. For purposes of clarity, not every component may be labeled in every drawing.
The drawings are provided for the purposes of illustration and explanation and are not
intended as a definition of the limits of the invention. In the drawings:
FIG. 1 is a cross-sectional view of a cable core according to one embodiment of
the invention;
FIG. 2 is perspective view of one embodiment of a perforated core according to
the invention;
FIG. 3 is a cross-sectional view af one embodiment of a cabie including the core
of FIG. I;
FIG. 4 is a cross-sectional view of another embodiment of a cable core used in
some embodiments of the cable of the invention;
FIG. 5 is an illustration of one embodiment of a cable comprising twisted pairs
having varying twist lays according to the invention;
FIG. 6 is a cross-sectional view of a twisted pair of insulated conductors;
FIG. 7 is a graph of impedance versus frequency for a twisted pair of conductors
according to the invention;
FIG. 8 is a graph of return loss versus frequency for the twisted pair of FIG. 7;
FIG. 9A is a perspective view of a cable having a dual-layer jacket according to
the invention;
FIG. 9B is a cross-sectional view of the cable of FIG. 9A, taken along line B-B in
FIG. 9A;
FIG. 10 is a perspective view of one embodiment of a bundled cable according to
the invention, illustrating oscillating cabling;
FIG. 11 is an illustration of another embodiment of a bundled cable including a
plurality of cables having interlocking striated jackets, according to the invention;
FIG. \2 is a perspective view of another embodiment of a bundled cable
including a plurality of cables having striated jackets, according to the invention; and

FIG. 13 is an illustration of yet another embodiment of cables having jackets with
inwardly extending projections, according to the invention.
DETAILED DESCRIPTION
Various illustrative embodiments and aspects thereof will now be described in
detail with reference to the accompanying figures. It is to be appreciated that this
invention is not limited in its application to the details of construction and the
arrangement of components set forth in the following description or illustrated in the
drawings. The invention is capable of other embodiments and of being practiced or of
being carried out in various ways. Also, the phraseology and terminology used herein is
for the purpose of description and should not be regarded as limiting. The use of
"including," "comprising," or "having," "containing", "involving", and variations
thereof herein, is meant to encompass the items listed thereafter and equivalents thereof
as well as additional items.
Referring to FIG. 1, mere is illustrated one embodiment of portions of a cable
including an extruded core 101 having a profile described below cabled into the cable
with four twisted pairs 103. Although the following description will refer primarily to a
cable that is constructed to include four twisted pairs of insulated conductors and a core
having a unique profile, it is to be appreciated that the invention is not limited to the
number of pairs or the profile used in mis embodiment. The inventive principles can be
applied to cables including greater or fewer numbers of twisted pairs and different core
profiles. Also, although this embodiment of the invention is described and illustrated in
connection with twisted pair data communication media, other high-speed data
communication media can be used in constructions of cable according to the invention.
As shown in FIG. 1, according to one embodiment of the invention, the extruded
core profile may have an initial shape of a "+", providing four spaces or channels 105,
one between each pair of fins 102 of the core 101. Each channel 105 carries one twisted
pair 103 placed within the channel 105 during the cabling operation. The illustrated core
101 and profile should not be considered limiting. The core 101 may be made by some
other process than extrusion and may have a different initial shape or number of channels
105. For example, as illustrated in FIG. 1, the core may be provided with an optional
central channel 107 that may carry, for example, an optical fiber element or strength
element 109. In addition, in some examples, more than one twisted pair 103 may be

placed in each channel 105.
The above-described embodiment can be constructed using a number of different
materials. While the invention is not limited to the materials now given, the invention is
advantageously practiced using these materials. The core material should be a
conductive material or one containing a powdered ferrite, the core material being
generally compatible with use in data communications cable applications, including any
applicable fire safety standards. In non-plenum applications, the core can be formed of
solid or foamed flame retardant polyolefin or similar materials. The core may also be
formed of non-flame retardant materials. In plenum applications, the core can be any
one or more of the following compounds: a solid low dielectric constant fluoropolymer,
e.g., ethylene chlortrifluoroethylene (E-CTFE) or fluorinated ethylene propylene (FEP),
a foamed fluoropolymer, e.g., foamed FEP, and polyvinyl chloride (PVC) in either solid,
low dielectric constant form or foamed. A filler is added to the compound to render the
extruded product conductive. Suitable fillers are those compatible with the compound
into which they are mixed, including but not limited to powdered ferrite, semiconductive
thermoplastic elastomers and carbon black. Conductivity of the core helps to further
isolate the twisted pairs from each other.
A conventional four-pair cable including a non-conductive core, such as the
Belden 1711A cable, reduces nominal crosstalk by up to 5 dB over similar, four-pair
cable without the core. By making the core conductive, crosstalk is reduced a further 5
dB. Since both loading of the core and jacket construction can affect crosstalk, these
numbers compare cables with similar loading and jacket construction.
As discussed above, the core 101 may have a variety of different profiles and
may be conductive or non-conductive. According to one embodiment, the core 101 may
further include features that may facilitate removal of the core 101 from the cable. For
example, referring to FIG. 2, the core 101 may be provided with narrowed, or notched,
sections 111, which are referred to herein as "pinch points." At the notched sections, or
pinch points, a diameter or size of the core 101 is reduced compared with the normal size
of the core 101 (at the non-pinch point sections of the core). Thus, the pinch points 111
provide points at which it may be relatively easy to break the core 101. The pinch points
111 may act as "perforations" along the length of the core, facilitating snapping of the
core at these points, which in turn may facilitate removal of sections of the core 101 from
the cable. This may be advantageous for being able to easily snap the core to facilitate

terminating the cable with, for example, a telephone or data jack or plug. In one
example, the pinch points 111 may be placed at intervals of approximately 0.5 inches
along the length of the cable. The pinch points 111 should be small enough such that the
twisted pairs may ride over the pinch points 111 substantially without dipping closer
together through the notched sections 111. In one example, the pinch points may be
formed during extrusion of the core by stretching the core for a relatively short period of
time each time it is desired to form a pinch point 111. Stretching the core during
extrusion results in "thinned" or narrowed sections being created in the core which form
the pinch points 111.
The cable may be completed in any one of several ways, for example, as shown
in FIG. 3. The combined core 101 and twisted pairs 103 may be optionally wrapped with
abinder 113 and then jacketed with a jacket 115 to form cable 117. In one example, an
overall conductive shield 117 can optionally be applied over the binder 111 before
jacketing to prevent the cable from causing or receiving electromagnetic interference.
The jacket 115 may be PVC or another material as discussed above in relation to the core
101. The binder 113 may be, for example, a dielectric tape which may be polyester, or
another compound generally compatible with data communications cable applications,
including any applicable fire safety standards. It is to be appreciated that the cable can
be completed without either or both of the binder and the conductive shield, for example,
by providing the jacket.
As is known in this art, when plural elements are cabled together, an overall twist
is imparted to the assembly to improve geometric stability and hetp'prevent separation.
In some embodiments of a process of manufacturing the cable of the invention, twisting
of the profile of the core along with the individual twisted pairs is controlled. The
process includes providing the extruded core to maintain a physical spacing between the
twisted pairs and to maintain geometrical stability within the cable. Thus, the process
assists in the achievement of and maintenance of high crosstalk isolation by placing a
conductive core in the cable to maintain pair spacing.
According to another embodiment, greater cross-talk isolation may achieved in
the construction of FIG. 4 by using a conductive shield 119, for example a metal braid, a
solid metal foil shield or a conductive plastic layer in contact with the ends 121 of the
fins 102 of the core 101. In such an embodiment, the core is preferably conductive.
Such a construction rivals individual shielding of twisted pairs for cross-talk isolation.

This construction optionally can advantageously include a drain wire 123 disposed in the
central channel 107, as illustrated in FIG. 4. In some examples, it may be advantageous
to have the fins 102 of the core 101 extend somewhat beyond a boundary defined by the
outer dimension of the twisted pairs 103. As shown in FIG. 4, this helps to ensure that
the twisted pairs 103 do not escape their respective channels 105 prior to the cable being
jacketed, and may also facilitate good contact between the fins 102 and the shield 119.
In the illustrated example, closing and jacketing the cable 117 may bend the ends 121 of
the fins 102 over slightly, as shown, if the core material is a relatively soft material, such
as PVC.
In some embodiments, particularly where the core 101 may be non-conductive, it
may be advantageous to provide additional crosstalk isolation between the twisted pairs
103 by varying the twist lays of each twisted pair 103. For example, referring to FIG. 5,
the cable 117 may include a first twisted pair 103a and a second twisted pair 103b. Each
of the twisted pairs 103a, 103b includes two metal wires 125a, 125b each insulated by an
insulating layer 127a, 127b. As shown in FIG. 5, the first twisted pair 103a may have a
twist lay length that is shorter than the twist lay length of the second twisted pair 103b.
As discussed above, varying the twist lay lengths between the twisted pairs in the
cable may help to reduce crosstalk between the twisted pairs. However, the shorter a
pair's twist lay length, the longer the "untwisted length" of that pair and thus the greater
the signal phase delay added to an electrical signal that propagates through the twisted
pair. It is to be understood that the term "untwisted length" herein denotes the electrical
length of the«twisted pair of conductors when the twisted pair of oohductors has no twist
lay (i.e., when the twisted pair of conductors is untwisted). Therefore, using different
twist lays among the twisted pairs within a cable may cause a variation in the phase delay
added to the signals propagating through different ones of the conductors pairs. It is to
be appreciated that for this specification the term "skew" is a difference in a phase delay
added to the electrical signal for each of the plurality of twisted pairs of the cable.
Therefore, a skew may result from the twisted pairs in a cable having differing twist lays.
As discussed above, the TIA/EIA has set specifications that dictate that cables, such as
category 5 or category 6 cables, must meet certain skew requirements.
In addition, in order to impedance match a cable to a load (e.g., a network
component), the impedance of a cable may be rated with a particular characteristic
impedance. For example, many radio frequency (RF) components may have

characteristic impedances of 50 or 100 Ohms. Therefore, many high frequency cables
may similarly be rated with a characteristic impedance of 50 or 100 Ohms so as to
facilitate connecting of different RF loads. The characteristic impedance of the cable
may generally be determined based on a composite of the individual nominal impedances
of each of the twisted pairs making up the cable. Referring to FIG. 6, the nominal
impedance of a twisted pair 103a may be related to several parameters including the
diameter of the wires 125a, 125b of the twisted pairs making up the cable, the center-to-
center distance d between the conductors of the twisted pairs, which may in turn depend
on the thickness of the insulating layers 127a, 127b, and the dielectric constant of the
material used to insulate the conductors.
The nominal characteristic impedance of each pair may be determined by
measuring the input impedance of the twisted pair over a range of frequencies, for
example, the range of desired operating frequencies for the cable. A curve fit of each of
the measured input impedances, for example, up to 801 measured points, across the
operating frequency range of the cable may then be used to determine a "fitted"
characteristic impedance of each twisted pair making up the cable, and thus of the cable
as a whole. The TIA/EIA specification for characteristic impedance is given in terms of
this fitted characteristic impedance. For example, the specification for a category 5 or 6
100 Ohm cable is 100 Ohms, +- 15 Ohms for frequencies between 100 and 350 MHz and
100 Ohms +- 12 Ohms for frequencies below 100 MHz.
In conventional manufacturing, it is generally considered more beneficial to
design and manufacture twisted pairs to achieve as close to the specified characteristic
impedance of the cable as possible, generally within plus or minus 2 Ohms. The primary
reason for this is to take into account impedance variations that may occur during
manufacture of the twisted pairs and the cable. The further away from the specified
characteristic impedance a particular twisted pair is, the more likely a momentary
deviation from the specified characteristic impedance at any particular frequency due to
impedance roughness will exceed limits for both input impedance and return loss of the
cable.
As the dielectric constant of an insulation material covering the conductors of a
twisted pair decreases, the velocity of propagation of a signal traveling through the
twisted pair of conductors increases and the phase delay added to the signal as it travels
through the twisted pair decreases. In other words, the velocity of propagation of the

signal through the twisted pair of conductors is inversely proportional to the dielectric
constant of the insulation material and the added phase delay is proportional to the
dielectric constant of the insulation material. For example, referring again to FIG. 6, for
a so-called "faster" insulation, such as fluoroethylenepropylene (FEP), the propagation
velocity of a signal through the twisted pair 103a may be approximately 0.69c (where c
is the speed of light in a vacuum). For a "slower" insulation, such as polyethylene, the
propagation velocity of a signal through the twisted pair 103a may be approximately
0.66c.
The effective dielectric constant of the insulation material may also depend, at
least in part, on the thickness of the insulating layer. This is because the effective
dielectric constant may be a composite of the dielectric constant of the insulating
material itself in combination with the surrounding air. Therefore, the propagation
velocity of a signal through a twisted pair may also depend on the thickness of the
insulation of that twisted pair. However, as discussed above, the characteristic
impedance of a twisted pair also depends on the insulation thickness.
Applicant has recognized that by optimizing the insulation diameters relative to
the twist lays of each twisted pair in the cable, the skew can be substantially reduced.
Although varying the insulation diameters may cause variation in the characteristic
impedance values of the twisted pairs, under improved manufacturing processes,
impedance roughness over frequency (i.e., variation of the impedance of any one twisted
pair over the operating frequency range) can be controlled to be reduced, thus allowing
for a design optimized for skew while still meeting the specification for impedance.
According to one embodiment of the invention, a cable may comprise a plurality
of twisted pairs of insulated conductors, wherein twisted pairs with longer pair lays have
a relatively higher characteristic impedance and larger insulation diameter, while twisted
pairs with shorter pair lays have a relatively lower characteristic impedance and smaller
insulation diameter. In this manner, pair lays and insulation thickness may be controlled
so as to reduce the overall skew of the cable. One example of such a cable, using
polyethylene insulation is given in Table 1 below.



This concept may be better understood with reference to FIGS. 7 and 8 which
respectively illustrate graphs of measured input impedance versus frequency and return
loss versus frequency for twisted pair 1, for example, twisted pair 103a, in the cable 117.
Referring to FIG. 7, a "fitted" characteristic impedance 131 for the twisted pair (over the
operating frequency range) may be determined from the measured input impedance 133
over the operating frequency range. Lines 135 indicate the category 5/6 specification
range for the input impedance of the twisted pair. As shown in FIG. 7, the measured
input impedance 133 falls within the specified range over the operating frequency range
of the cable 117. Referring to FIG. 8, there is illustrated a corresponding return loss
versus frequency plot for the twisted pair I03a. The line 137 indicates the category 5/6
specification for return loss over the operating frequency range. As shown in FIG. 8, the
measured return loss 139 is above the specified limit (and thus within specification) over
the operating frequency range of the cable. Thus, the characteristic impedance could be
allowed to deviate further from the desired 100 Ohms, if necessary, to reduce skew.
Similarly, the twist lays and insulation thicknesses of the other twisted pairs may be
further varied to reduce the skew of the cable while still meeting the impedance
specification.
According to another embodiment, a four-pair cable was designed, using slower
insulation material (e.g., polyethylene) and using the same pair lays as shown in Table 1,
where all insulation diameters were set to 0.041 inches. This cable exhibited a skew
reduction of about 8 ns/100 meters (relative to the conventional cable described above -
this cable was measured to have a worst case skew of approximately 21 ns whereas the
conventional, impedance-optimized cable exhibits a skew of approximately 30 ns or
higher), yet the individual pair impedances were within 0 to 2.5 ohms of deviation from
nominal, leaving plenty of room for further impedance deviation, and therefore skew
reduction.
Allowing some deviation in the twisted pair characteristic impedances relative to
the nominal impedance value allows for a greater range of insulation diameters. Smaller
diameters for a given pair lay results in a lower pair angle and shorter non-twisted pair

length. Conversely, larger pair diameters result in a higher pair angles and longer non-
twisted pair length. Where a tighter pair lay would normally require an insulation
diameter of 0.043" for 100 ohms, a diameter of .041" would yield a reduced impedance
of about 98 ohms. Longer pair lays using the same insulation material would require a
lower insulation diameter of about 0.039" for 100 ohms, and a diameter of 0.041" would
yield about 103 ohms. As shown in FIGS. 7 and 8, allowing this "target" impedance
variation from 100 Ohms may not prevent the twisted pairs, and the cable, from meeting
the input impedance specification, but may allow improved skew in the cable.
According to another embodiment, illustrated in FIGS. 9A and 9B, the cable 117
may be provided with a dual-layer jacket 141 comprising a first, inner layer 143 and a
second, outer layer 145. An optional conductive shield 147 may be placed between the
first and second jacket layers 143, 145, as illustrated. The shield 147 may act to prevent
crosstalk between adjacent or nearby cables, commonly called alien crosstalk. The
shield 147 may be, for example, a metal braid or foil that extends partially or
substantially around the first jacket layer 143 along the length of the cable. The shield
147 may be isolated from the twisted pairs 103 by the first jacket layer 143 and may thus
have little impact on the twisted pairs. This may be advantageous in that small or no
adjustment may need to be made to, for example conductor or insulation thicknesses of
the twisted pairs 103. The first and second jacket layers may be any suitable jacket
material, such as, PVC, fluoropolymers, fire and/or smoke resistant materials, and the
like. In this embodiment, because the shield is isolated from the twisted pairs 103 and
the separator 101 by the first jacket layer 143, the separator 101 may be conductive or
non-conductive.
According to another embodiment, several cables such as those described above
may be bundled together to provide a bundled cable. Within the bundled cable may be
provided numerous embodiments of the cables described above. For example, the
bundled cable may include some shielded and some unshielded cables, some four-pair
cables and some having a different number of pairs. In addition, the cables making up
the bundled cable may include conductive or non-conductive cores having various
profiles. In one example, the multiple cables making up the bundled cable may be
helically twisted together and wrapped in a binder. The bundled cable may include a rip-
cord to break the binder and release the individual cables from the bundle.

According to one embodiment, illustrated in FIG. 10, the bundled cable 151 may
be cabled in an oscillating manner along its length rather than cabled in one single
direction along the length of the cable. In other words, the direction in which the cable is
twisted (cabled) along its length may be changed periodically from, for example, a
clockwise twist to an anti-clockwise twist, and vice versa. This is known in the art as SZ
type cabling and may require the use of a special twisting machine known as an
oscillator cabler. In some examples of bundled cables 151, each individual cable 117
making up the bundled cable 151 may itself be helically twisted (cabled) with a
particular cable lay length, for example, about 5 inches. The cable lay of each cable may
tend to either loosen (if in the opposite direction) or tighten (if in the same direction) the
twist lays of each of the twisted pairs making up the cable. If the bundled cable 151 is
cabled in the same direction along its whole length, this overall cable lay may further
tend to loosen or tighten the twist lays of each of the twisted pairs. Such altering of the
twist lays of the twisted pairs may adversely affect the performance of at least some of
the twisted pairs and/or the cables 117 making up the bundled cable 151. However,
helically twisting the bundled cable may be advantageous in that it may allow the
bundled cable to be more easily bent, for example, in storage or when being installed
around corners. By periodically reversing the twist lay of the bundled cable, any effect
of the bundled twist on the individual cables may be substantially canceled out. In one
example, the twist lay of the bundled cable may be approximately 20 inches in either
direction. As shown in FIG. 10, the bundled cable may be twisted for a certain number
of twist lays in a first direction (region 153), then not twisted for a certain length (region
155), and then twisted in the opposite direction for a number of twist lays (region 157).
Referring to FIG. 11, there is illustrated another embodiment df a bundled cable
161 according to the invention. In this embodiment, one or more of the individual cables
117 making up the bundled cable 161 may have a striated jacket 163, as shown. The
striated jacket 163 may have a plurality of protrusions 165 spaced about a circumference
of the jacket 163. In one example, the cables 117 may not be twisted with a cable lay. In
this example, the protrusions 165 may be constructed such that the protrusions 165a of
one jacket 163a may mate with the protrusions 165b of another jacket 163b so as to
interlock two corresponding cables 117a, 117b together. Thus, the individual cables 117
making up the bundled cable 161 may "snap" together, possibly obviating the need for a

binder to keep the bundled cable 161 together. This embodiment may be advantageous
in that the cables 117 may be easily separated from one another when necessary.
In another example, the individual cables 117 may be helically twisted with a
cable lay. In this example, the protrusions 165 may form helical ridges along the length
of the cables 117, as shown in FIG. 12. The protrusions 165 may thus serve to Anther
separate one cable 117a from another 117b, and may thereby act to reduce alien crosstalk
between cables 117a, 117b. The plurality of cables 117 may be wrapped in, for example,
a binder 167 to bundle the cables 117 together and form the bundled cable 161.
According to another embodiment, the cable 117 may be provided with a striated
jacket 171 having a plurality of inwardly extending projections 173, as shown in FIG. 13.
Such a jacket construction may be advantageous in that the projections may result in
relatively more air separating the jacket 171 from the twisted pairs 103 compared with a
conventional jacket. Thus, the jacket material may have relatively less effect on the
performance characteristics of the twisted pairs 103. For example, the twisted pairs may
exhibit less attenuation due to increased air surrounding the twisted pairs 103. In
addition, because the jacket 171 may be held further away from the twisted pairs 103 by
the protrusions 173, the protrusions 173 may help to reduce alien crosstalk between
adjacent cables 117 in a bundled cable 175. The cables 117 may again be wrapped in.
for example, a polymer binder 177 to form the bundled cable 175.
Having thus described several aspects of at least one embodiment of this
invention, it is to be appreciated various alterations, modifications, and improvements
will readily occur to those skilled in the art. For example, any of the'cables described
herein may include any number of twisted pairs and any of the jackets, insulations and
separators shown herein may comprise any suitable materials. In addition, the separators
may be any shape, such as, but not limited to, a cross- or star-shape, or a flat tape etc.,
and may be positioned within the cable so as to separate one or more of the twisted pairs
from one another. Such and other alterations, modifications, and improvements are
intended to be part of this disclosure and are intended to be within the scope of the
invention. Accordingly, the foregoing description and drawings are by way of example
only.

We claim:
1. A method of manufacture o f a data cable comprising steps of.
extruding a core from a core material;
arranging the core together with a plurality of twisted pairs of insulated conductors having a
first twisted pair and a second twisted pair, wherein the core is disposed between the plurality of
twisted pairs of insulated conductors so as to separate the first twisted pair from the second twisted
pair along a length of the cable; and
jacketing the core and the plurality of twisted pairs of insulated conductors so as to form the
data cable;
wherein the step of extruding the core comprises stretching the core material at a plurality of
intervals during extrusion so as to form a corresponding plurality of pinch points along a length of the
core such that a diameter of the core at the pinch points is substantially reduced relative to a maximum
diameter of the core;
wherein the step of jacketing comprises jacketing the core and the plurality of twisted pairs of
insulated conductors with a jacket having a plurality of inwardly projecting protrusions disposed about
a circumference of the jacket and arranged to keep the plurality of twisted pairs of insulated
conductors away from an inner circumference of the jacket.
2. The method as claimed in claim \, wherein the step of extruding the core comprises extruding
the core such that the core comprises a plurality of fins extending outwardly from a center of the core
and defining a plurality of channels, and wherein the step of arranging comprises arranging the core
and the plurality of twisted pairs of insulated conductors such that at least one of the twisted pairs of
insulated conductors is disposed within each of the plurality of channels.
3. A method of forming a bundled cable comprising a plurality of cables in a binder, wherein the
plurality of cables comprise the cable formed by the method as claimed in claim 1.
4. A bundled cable comprising:
a first cable comprising a first plurality of twisted pairs of insulated conductors and a first
separator arranged between the first plurality of twisted pairs so as to separate one twisted pair of the
first plurality of twisted pairs from others of the first plurality of twisted pairs, the first cable having a
first jacket; and

a second cable comprising a second plurality of twisted pairs of insulated conductors and a
second separator arranged between the second plurality of twisted pairs so as to separate one twisted
pair of the second plurality of twisted pairs from others of the second plurality of twisted pairs, the
second cable having a second jacket;
wherein each of the first and second jackets comprises a plurality of protrusions extending
inwardly toward a center of the first and second cables, respectively; and
wherein the plurality of protrusions are configured to keep the first and second pluralities of
twisted pairs of insulated conductors away from an inner circumference of the first and second jackets,
respectively.
5. The bundled cable as claimed in claim 4, wherein the first and second separators are non-
conductive.
6. The bundled cable as claimed in claim 4, wherein the bundled cable is helically twisted in an
oscillating manner such that the bundled cable comprises a first region having a clockwise twist lay
and a second region having an anticlockwise twist lay.
7. A cable comprising:
a plurality of twisted pairs of insulated conductors having a first twisted pair and a second
twisted pair;
a separator disposed among the plurality of twisted pairs of insulated conductors so as to
separate the first twisted pair from the second twisted pair; and
a jacket surrounding the plurality of twisted pairs of insulated conductors and the jacket;
wherein the jacket comprises a plurality of protrusions extending inwardly from an inner
circumferential surface of the jacket, and wherein the plurality of protrusions are arranged to keep the
plurality of twisted pairs of insulated conductors away from the inner circumferential surface of the
jacket.

Documents:

01303-kolnp-2006 correspondence others-1.1.pdf

01303-kolnp-2006 form-3-1.1.pdf

01303-kolnp-2006- correspondence-1.2.pdf

01303-kolnp-2006-abstract.pdf

01303-kolnp-2006-asignment.pdf

01303-kolnp-2006-claims.pdf

01303-kolnp-2006-correspondence other.pdf

01303-kolnp-2006-description (complete).pdf

01303-kolnp-2006-drawings.pdf

01303-kolnp-2006-form-1.pdf

01303-kolnp-2006-form-18.pdf

01303-kolnp-2006-form-3.pdf

01303-kolnp-2006-form-5.pdf

01303-kolnp-2006-international publication.pdf

01303-kolnp-2006-international search authority report.pdf

01303-kolnp-2006-pct form.pdf

1303-KOLNP-2006-ABSTRACT-1.1.pdf

1303-KOLNP-2006-ABSTRACT.pdf

1303-KOLNP-2006-AMANDED CLAIMS-1.1.pdf

1303-KOLNP-2006-AMANDED CLAIMS.pdf

1303-kolnp-2006-assignment.pdf

1303-KOLNP-2006-CANCELLED PAGES.pdf

1303-KOLNP-2006-CORRESPONDENCE 1.1.pdf

1303-KOLNP-2006-CORRESPONDENCE 1.2.pdf

1303-KOLNP-2006-CORRESPONDENCE-1.1.pdf

1303-KOLNP-2006-CORRESPONDENCE-1.2.pdf

1303-kolnp-2006-correspondence-1.3.pdf

1303-KOLNP-2006-DESCRIPTION (COMPLETE)-1.1.pdf

1303-KOLNP-2006-DESCRIPTION (COMPLETE).pdf

1303-KOLNP-2006-DRAWINGS-1.1.pdf

1303-KOLNP-2006-DRAWINGS.pdf

1303-kolnp-2006-examination report.pdf

1303-KOLNP-2006-FORM 1-1.1.pdf

1303-KOLNP-2006-FORM 1.pdf

1303-kolnp-2006-form 18.pdf

1303-KOLNP-2006-FORM 2-1.1.pdf

1303-KOLNP-2006-FORM 2.pdf

1303-kolnp-2006-form 3-1.1.pdf

1303-KOLNP-2006-FORM 3.pdf

1303-kolnp-2006-form 5.pdf

1303-KOLNP-2006-FORM-27.pdf

1303-kolnp-2006-granted-abstract.pdf

1303-kolnp-2006-granted-claims.pdf

1303-kolnp-2006-granted-description (complete).pdf

1303-kolnp-2006-granted-drawings.pdf

1303-kolnp-2006-granted-form 1.pdf

1303-kolnp-2006-granted-form 2.pdf

1303-kolnp-2006-granted-specification.pdf

1303-KOLNP-2006-PA-1.1.pdf

1303-KOLNP-2006-PA.pdf

1303-KOLNP-2006-PETITION UNDER RULE 137.pdf

1303-KOLNP-2006-REPLY TO EXAMINATION REPORT-1.1.pdf

1303-kolnp-2006-reply to examination report-1.2.pdf

1303-KOLNP-2006-REPLY TO EXAMINATION REPORT.pdf

abstract-01303-kolnp-2006.jpg


Patent Number 246710
Indian Patent Application Number 1303/KOLNP/2006
PG Journal Number 11/2011
Publication Date 18-Mar-2011
Grant Date 11-Mar-2011
Date of Filing 17-May-2006
Name of Patentee BELDEN TECHNOLOGIES, INC.
Applicant Address 7701 FORSYTH BLVD., SUITE 800, ST. LOUIS, MISSOURI
Inventors:
# Inventor's Name Inventor's Address
1 CLARK WILLIAM T 37 STERLING STREET, LANCASTER, MA 01523
PCT International Classification Number H01B 11/08
PCT International Application Number PCT/US2004/037509
PCT International Filing date 2004-11-09
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 10/705,672 2003-11-10 U.S.A.